JPH084794B2 - Sprinkling filter type bioreactor and ethanol fermentation method using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sprinkling filter type bioreactor used for causing a substrate such as glucose to act on a microorganism to efficiently produce a useful substance, and a bioreactor using the same. It was related to the ethanol fermentation method.

(Prior Art) In a bioreactor in which a substrate such as sugar solution is allowed to act on immobilized microorganisms to produce useful substances, the amount of immobilized microorganisms present in the reactor is an important factor that determines productivity. Therefore, conventionally, as shown in FIG. 5, an immobilization carrier obtained by entrapping microorganisms in a gel of alginic acid or K-carrageenan, or a honeycomb-like or granular immobilization carrier formed of porous ceramics (10).
A bioreactor in which the reactor is immersed under the liquid surface of the reactor (11) is used.

However, in the case of a bioreactor in which the immobilized carrier is immersed below the liquid surface, if the packing density of the carrier is increased, that is, if the particle size of the carrier is reduced, or if the honeycomb pitch is decreased, a drift of the fermentation liquid occurs and the liquid Occurrence of clogging by the microorganisms that settle in the non-flowing portion, and that portion becomes a dead space, leading to a decrease in productivity. On the contrary, when the particle size of the carrier is increased or the honeycomb pitch is increased, the effective surface area is reduced and the amount of immobilized microorganisms does not increase, and the productivity does not increase so much. Therefore, a bioreactor using such a conventional immobilization carrier (10) has not reached satisfactory productivity.

Furthermore, a bioreactor using facultative anaerobic bacteria, especially an ethanol fermentation device using yeast cells, does not grow or slows the growth of the cells unless oxygen is supplied to the inside of the reactor. Although it decreases, in a bioreactor in which a honeycomb-shaped or granular immobilization carrier (10) formed of porous ceramics is immersed in the liquid flow of a reactor (11), as shown in FIG. When aeration is performed from the air diffuser plate (12), the flow velocity of the liquid flowing through the gap between the honeycombs or the carrier particles is increased, which causes the problem that the bacterial cells are separated from the surface of the immobilized carrier (10).

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and can immobilize a large amount of microorganisms in a reactor, and can achieve higher productivity. The present invention has been completed to provide a bioreactor capable of giving sufficient oxygen to a microorganism to promote its growth and an ethanol fermentation method using the bioreactor.

(Means for Solving the Problem) The above problem is that the granular yeast immobilization carrier obtained by crushing porous ceramics to a particle size of 1.5 to 20 mm is randomly packed in the reactor to form a packed bed, and the microorganism is A spraying nozzle and an air intake port are provided above the packed bed of the immobilizing carrier, and further a circulation line is provided for spraying the fermentation method sucked from the bottom of the reactor by a pump from this spray nozzle. It can be achieved by a floor bioreactor.

(Example) Next, this invention is demonstrated still in detail with the Example of the ethanol fermentation using yeast.

In Fig. 1, (1) shows that the value of diameter / carrier filling height is
A cylindrical reactor of about 0.1 to 0.5, and (2) is a packed bed of the yeast immobilization carrier formed inside the reactor (1). The packed bed (2) of the present invention is obtained by crushing porous ceramics having a high ability to immobilize bacterial cells to a particle size of 1.5 to 20 mm, and randomly packing the reactor (1) while leaving a required upper space (7). It was done. Further, when the value of diameter / carrier filling height is 0.5 or more, there are too many reactor parts under favorable conditions and ethanol fermentation, which is an anaerobic fermentation, is not carried out and the yield of ethanol against sugar decreases. . On the other hand, when the ratio is 0.1 or less, the anaerobic portion is too much, the effect of the spray nozzle cannot be obtained, and it is substantially difficult to construct the reactor.

For porous ceramics, the total pore volume is 0.1 to 1.5.
Regarding cc / g and pore size, the pores with the minimum size (2 μm) or more of the yeast to be immobilized are the whole pores (100 μm or less)
It is preferable to use a ceramics of 70% or more (volume ratio). If the total pore volume is less than 0.1 cc / g, the amount of immobilized cells will be small and the ethanol production rate will decrease as shown in Fig. 2. Conversely, the total pore volume will be less than 1.5c.
When it exceeds c / g, the mechanical strength is lowered as shown in FIG. 3 and it cannot be used. If the pore size is less than 2 μm, the yeast cells cannot be immobilized due to the size of the yeast cells themselves. Therefore, at least 70% or more of the total pores are required to have pores having a size larger than that of the yeast cells. Furthermore, the particle size of the porous ceramics is 1.5 to 2
The value of 0 mm is that if it is less than 1.5 mm, the filling degree becomes too dense and the flow of the liquid is bad, which causes uneven flow as in the conventional case.On the contrary, if it exceeds 20 mm, the internal volume that does not contribute to ethanol fermentation becomes large. The reason is that the ethanol production rate also decreases.

A spray nozzle (3) for spraying the fermentation liquid toward the packed bed (2) is provided above the packed bed (2) of the yeast immobilization carrier. (4) is the pump (5)
This is a circulation line for spraying the fermented liquid sucked from the bottom of the reactor (1) by this spray nozzle (3), and a substrate supply pipe (6) is connected in the middle thereof.

At the upper end of the reactor (1), the upper space (7)
An air intake (8) for supplying oxygen to
The structure is such that the fresh air filtered by the filter can be taken into the reactor (1). In particular, in the early stage of the operation, bacterial cells are grown, so that positive supply of air from the air intake port (8) can shorten the reactor start-up period. In addition, when the ethanol productivity of the reactor decreases due to continuous fermentation for a long period of time, the activity can be quickly recovered by positively supplying air from the air intake port (8).

(Operation) In the sprinkling filter type bioreactor of the present invention thus configured, the microorganisms are immobilized on the granular microorganism-immobilizing carrier of the packed bed (2) by a conventional method, and then the substrate supply pipe (6) is used. A substrate mixed with a nutrient source is supplied into the reactor (1) so that useful substances are produced by the action of microorganisms.

The fermented liquor, which is a mixture of the produced useful substance and the substrate, flows down to the bottom of the reactor (1), is sucked up by a pump (5) from here, and is provided above the packed bed (2). The product is sprayed again from the spray nozzle (3), the concentration of the product is gradually increased while repeating such circulation, and a part of the product is taken out from the fermentation liquid take-out port (9).

As described above, in the present invention, the fermentation liquid can be made to flow uniformly from the upper side to the lower side, so that clogging does not occur. Moreover, the fermented liquid takes in outside air when sprayed from the spray nozzle (3) and is sprayed on the packed bed (2) in an oxygen-rich state, and oxygen can be supplied from the air intake (8). Therefore, sufficient oxygen is also supplied to the microorganisms immobilized in the packed bed (2), and the growth thereof is promoted. Therefore, the activity of the microorganism can be maintained at a high level for a long period of time.

As a result of the above, according to the sprinkling filter type bioreactor of the present invention, high productivity of the target substance can be obtained as shown by white circles in FIG. For comparison, the productivity of the conventional bioreactor is shown by a black circle in FIG.

(Effects of the invention) As described above, the present invention can increase the amount of immobilized cells, so that high productivity of the target substance can be secured, clogging does not easily occur, and oxygen is sufficiently supplied. Therefore, in addition to the advantages that the activity of microorganisms can be stabilized for a long period of time, the amount of free microorganisms is reduced, so that there is an advantage that a clear fermentation liquor can be obtained.

Therefore, the present invention, as a sprinkling filter-type bioreactor that solves the conventional problems and an ethanol fermentation method using the same, greatly contributes to industrial development.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention, FIG. 2 is a graph showing the relationship between the total pore volume of porous ceramics and ethanol production rate, and FIG. FIG. 4 is a graph showing the relationship between pore volume and transverse rupture strength, FIG. 4 is a graph showing ethanol productivity when the sprinkling bed bioreactor of the present invention and a conventional bioreactor are used for ethanol fermentation, FIG. FIG. 4 is a schematic cross-sectional view showing an example of a conventional bioreactor. (1): Reactor, (2): Packed bed, (3): Spray nozzle, (4): Circulation line, (5): Pump

Continuation of front page (56) Reference JP-A-60-120988 (JP, A) JP-A-64-43189 (JP, A) JP-A-61-19481 (JP, A) JP-A-64-2567 (JP , A)

Claims (5)

[Claims] 1. A reactor (1) comprising a granular carrier for immobilizing microorganisms obtained by crushing porous ceramics to a particle size of 1.5 to 20 mm.
A packed bed (2) is randomly packed in the inside, and a spray nozzle (3) and an air intake (8) are provided above the packed bed (2) of the carrier for immobilizing microorganisms, and a pump (5) is further provided. ) Is provided with a circulation line (4) for spraying the fermentation liquid sucked from the bottom of the reactor (1) through the spray nozzle (3). 2. Pores having a total pore volume of 0.1 to 1.5 cc / g and having a pore size of at least the minimum dimension of the microorganism to be immobilized, by volume ratio, being 70% or more of the total pores. The sprinkling filter type bioreactor according to claim 1, wherein the fine ceramics is used. 3. The sprinkled filter bioreactor according to claim 1, wherein the microorganism to be immobilized is a facultative anaerobic bacterium. 4. The value of reactor diameter / carrier packing height is 0.
The sprinkler filter bed type bioreactor according to claim 1, which is 1 to 0.5. 5. The microorganism used is yeast, and the pore diameter of the porous ceramics, which is a carrier for immobilizing the yeast, is 10
70% or more of the pores of 0 μm or less have a diameter of 2 to 100 μm
The ethanol fermentation method for producing ethanol using the sprinkling filter bioreactor according to any one of claims 1, 2 and 4, which is within the range.